Compressed-air driven drill



Sept' 10, 1.946 R. w. MANN Erm. 2,407,613

COMPRESSED AIR-DRIVEN DRILL Filed Dec. 21, 1943 'zev sheets-sheet 1 i' Attorneys Sept. 10, 1946. R. w. MANN ETL I 2,407,613

` coMPREssED AIR-DRIVEN DRILL Filed Dec. 21, 1943 2 Sheets-7Sheet 2 INF- Y'IIIA- I nveniors Patented Sept. 10, 1946 COMPRESSED-AIR DRIVEN DRILL Reginald William Mann, Monkseaton, and Robert Clough Wiles, Newcastle-on-Tyne, England, assignors to Victor Products, (Wallsend) Limited, a British company Application December 21, 1943, Serial No. 515,136 In Great'Britain January 25, 1943 2 Claims.

This invention relates to rotary drills of the kind comprising a compressed-air motor. Drills with motors of the type having a rotor with sliding vanes turning about an eccentric axis in its cylinder have been used in the engineering industry, but hitherto they have not been found satisfactory for use, particularly in mines or quarries, mainly because of inadequate lubrication of the motor, and/or `the excessive escape of air and moisture into the gearing.

In drills of this character hitherto used lubrication has been effected by providing an oil reservoir in the casing of the drill with a Venturitype connection to the main compressed-air supply so that oil is entrained in the current of air. It has been found, however, that only a very small proportion of this oil reaches the parts most in need of lubrication, namely the vanes and the slots in the rotor in which they slide, the bulk of the oil being blown out with the exhaust air and wasted. In consequence the oil in the reservoir is quickly used up and requires frequent renewal.

It is usual in such drills to ley-pass `a small proportion of the air to a recess in the end plate of the rotor for the purpose of pushing the vanes outwards in their slots, particularly during starting when centrifugal force is not in action or is insufcient to keep the vanes pressed outwards. We have now found that by supplying an adequate proportion of lubricant to such by-passed air only, and no lubricant to the main body of air which serves to operate the motor, efficient lubrication can be insured while lubricant is conserved, and the drill can be used for a much longer time without requiring re-charging with lubricant.

It is the principal object of the invention therefore to provide a rotary drill of the type employing a motor of the sliding vane type actuated by compressed air, with means for feeding lubricant to a small proportion only of such compressed air, and with passages for conveying the air charged with lubricant to the motor in a position such that it acts to press the vanes outwardly as the rotor of the compressed air motor turns in its casing.

A further object is to provide convenient means for controlling the proportion of the air bypassed from the main supply of compressed air, and for regulating the degree to which said bypassed air is saturated with lubricant.

A still further object is to restrict the passage of compressed air from said motor into the gear box enclosing the gears through which the drill chuck is driven, and to provide convenient means for venting said gear box to prevent appreciable rise of pressure therein while avoiding entry of foreign matter from outside.

With these and other objects in view the drill forming the subject of this invention has been designed and constructed substantially in the manner illustrated in the accompanying drawings wherein:

Figure l is a longitudinal sectional elevation of a compressed air drill showing the oil reservoir and other features of the invention applied thereto;

Figure 2 is a cross section on the line 2--2 of Figure l, looking toward the left;

Figure 3 is a view of the righthand end plate of the motor; and

Figure 4 shows a modification of a part of the motor casing in longitudinal section.

Referring to the drawings; the drill illustrated is of a type in which compressed air is supplied through a cock 5 to a cavity at 6 in the motor casing I2, whence it passes through ports at 'I in the cylinder liner 8 to the working space of a vane motor. This consists of a rotor I0 with vanes 9 operating in radial slots therein as usual, the rotor being eccentrically arranged in its cylinder. The exhaust of used air takes place through slots at II in the other side of the liner 8. The air reaches the cavity 6 through an aperture at I5 in a partition wall and the rate at which the air can pass this aperture is controlled by a plug member I3 which screws into the outer wall of the cavity 6 and can be adjusted to come nearer to or further from the aperture I5 by using washers or collars I4 of different widths between the head of the plug member I3 and the wall into which it screws. This adjustment is made when the purpose for which the drill will be used is determined, namely according to whether it is required for stone, hard coal or soft coal and the like, and before the flanged casing 24 is secured by bolts 25 to the motor casing I2. The setting of the plug I3 by its collar i4 limits the range of air admission, and consequently the maximum drilling speeds as is required for the different materials to be drilled, and the diiierent forms of bits used for each of these materials.

A small proportion of the air supplied to the drill is directed through the central bore of plug I3 and a reduced bore at 26 to a compartment I6 which is lled with absorbent material such as gauze or cotton wool soaked with oil. The oil is supplied as required through a filling aperture at II. The air charged with oil passes through toms of the slots in which the vanes 9 work, and

thus keep them forced outwardly as the rotor I turns. It is not found necessary for lubricating the motor to impregnate with oil even the whole ofthe air fed in this way to the recess 22 and" the inner ends of the vanes 9, and some air may be by-passed from the point of entry to chamber I6 around the end of the plug member I3, where a gap is shown at 23, leading into the chamber' I9. This Icy-passed air practically picks up no oil from the absorbent pad in chamber I6 as it flows out around its point of entry.

Additional adjustable means for by-passing air may be provided if desired, as shown in Figure 4, Where 21 represents a needle valve adjustable from the outside before the casing 24 containing the compartments I6 and I9 is assembled on the drill, for permitting air to be bypassed directly from cavity E to the chamber I9. In this case also the end 28 of plug i3 is shown as a separate iitting so that its size and bore can be determined according to the amount of air which is needed yto be impregnated with oil for lubricating the motor.

` The rotor shaft is connected to epicyclic reduction gears 39, 4i) in gearbox 29, the drive being transmitted through the spindle 3i! coupled to the shaft 3| which carries the chuck 32 for the drill bits as usual. The drill is shown as being provided with lugs 33 and 34 for the stem 35 of the Vforce feed mechanism which is used when the drill is mounted on a braced support and fed up to its work by a ratchet feed 31 operated by a handle 36 in the Well known way. The drill also has a rubber shoulder pad'38 attached to the'face of'compartment Il for use when'the drill4 is manipulated byhand.

Leakage of air from the motor into thegearbox 29 is largely minimised by providing the rotor I0 with a disc or balile 4I which turns with the rotor in arecess at 42 in the end cover 43 surbetween the baffle 4I and the recess in which it turns can be made very small so that very little air can pass through into the gearbox. Any substantial rise of pressure in the gear box is prevented by venting it through 'a passage 45 into a compartment 46 in the rotor casing, which in turn is Vented to the outside through a hole at 4l. This avoids any risk of dirt entering the y gearbox through the venting aperture.

It will be evident that many details of the construction illustrated can be varied according 'to "the type of` drill to which the invention is l applied'.

rounding the ball bearing 44. The' clearances u We claim:

l. In a rotary drill adapted to be driven by compressed air, the combination of a rotor with a plurality of radial slots therein, vanes adapted to slide radially of the rotor one in each slot thereof, a surrounding casing with end walls and an internal circumferential wall disposed eccentrically to said rotor and in which theA vanes of the rotor are adapted to slide, an inlet for compressed air, a compartment associated with said casing adapted to contain an absorbent material soaked in lubricant fluid, an adjustable plug member associated with said compressed air inlet and adapted to be set in such a manner as to control the rate at which compressed air can enter said casing, a passage through said plug member leading to said compartment and adaptedV to by pass a small proportion of the `compressed air into the said compartment,l a passage leading from said compartment to a recess in one end Wall of saidsurrounding casing adjacent the bases of said slots in said rotor in which said vanes are mounted to slide, said recess being so disposed as to permit compressed air soaked with lubricant from said compartment to enter said slotsin the rotor, to press out said vanes radially in said slots, and to apply lubricant thereto as theY rotor turns in its casing.

2; In a rotary drill as claimed in claim l, an additional passage and an adjustable valve therein adapted to permit an additional portion of compressed air from said inlet to pass to said `recess in the end Wall of said casing withoutipassing 

